Implantable intraluminal prosthesis

ABSTRACT

An implantable intraluminal prosthesis assembly is provided for use in repairing or replacing damaged or diseased portions of a blood vessel or other like vessel. The prosthesis includes an expandable stent/graft combination, with a pair of stents at either end of the graft, and further includes a plurality of struts extending between and interconnecting the stents, and radial spaced about the inner surface of the graft. As such, the implantable prosthesis is provided with internal support for the graft when in a compressed state during implantation and is further provided with radial support along the length of the graft after implantation.

FIELD OF THE INVENTION

[0001] The present invention relates generally to an expandableintraluminally implantable prosthesis. More particularly, the presentinvention relates to a radially supported graft/stent combination whichmay be intraluminally implanted in a minimally invasive procedure torepair or replace a damaged vessel of the vascular system.

BACKGROUND OF THE INVENTION

[0002] It has long been known to employ intraluminally implantableprosthetic devices to repair or replace a damaged or diseased portion ofa body lumen such as a blood vessel. Intraluminal implantation in aminimally invasive procedure permits such repair without the necessityof major surgical intervention. Typically, such implantation involvesthe use of a delivery system employed directly percutaneously or inother minimally invasive procedures, such as cut downs. In this manner,endovascular structures may be implanted by use of such a deliverysystem from a location remote from the damaged area. Intraluminalimplantation in this manner greatly minimizes the risks inherent inmajor surgical implantation as it is less traumatic, less complicated,and generally a safer procedure. The prosthesis so delivered establishesa conduit which bridges the damaged portion of the vessel, therebyre-establishing blood flow therethrough without risk of further damageto the vessel. While vascular repair is one of the more commonapplications of an intraluminal prosthesis, such prosthesis may also bedesigned for use in other body lumens where repair is required.

[0003] The art has seen a wide variety of intraluminally deliverableprosthetic devices. Typically, these devices may include a tubular graftwhich is designed to span the damaged site of the vessel to permit bloodflow therethrough. Such a graft is generally a compressible, flexiblemember which may be compressed or compacted into a small configurationso as to permit intraluminal delivery. In order to securely anchor thegraft in place, the prosthesis may also include one or more stentsattached to the graft itself. A stent is a compressible spring-likemember which may be self-expanding such that when the prosthesis isdeployed at its proper location, the stent expands so as to expand thegraft into contact with the lumen to be repaired. The stent also servesto anchor the graft in place, thereby preventing migration of theprosthesis once the prosthesis is properly implanted.

[0004] An endovascular prosthesis employing a graft/stent combinationwhich may be deliverable intraluminally via a delivery catheter is shownand described in U.S. Pat. No. 5,387,235, issued to Chuter. This patentdescribes a radially self-expandable prosthesis, including a woven,multi-filament polyester tubular graft which is supported by a springassembly. The spring assembly includes individual stents at each end ofthe graft. A sheath is used to hold the graft and stents in a compressedcondition so that it may be delivered intraluminally via the deliverycatheter. Once properly located, the sheath is removed and theprosthesis is allowed to self-expand within the vessel across thedamaged area. The individual stents may include outwardly directed barbswhich anchor into the vessel securely positioning the prosthesis andpreventing migration thereof.

[0005] The apparatus described in the '235 patent serves adequately toimplant a prosthesis intraluminally across a damaged vessel. However, asthe graft is supported at spaced apart opposite ends thereof by theindividual stents, the central portion of the graft is unsupported. Suchunsupported central extent is subject to collapsing, kinking or folding,especially as the prosthesis traverses a tortuous path duringimplantation. Also, as separate spaced apart stents are employed at eachend of the graft, it is possible for the stents to migrate axiallyrelative to one another during implantation.

[0006] One attempt to address problems such as these in a percutaneouslyimplantable prosthesis is shown in U.S. Pat. No. 5,282,824, issued toGianturco. A graft/stent combination is disclosed where the spaced apartstents supporting opposed ends of the graft are connected by a singleelongate rod. The single rod is designed to resist the contraction ofthe assembly along the longitudinal axis when the assembly is radiallycompressed and/or expanded. While the design of the stent assembly ofthe '824 patent serves to maintain axial spacing between the spacedapart stents, the single rod connecting the stents offers little or noradial support to the graft positioned thereover. Thus, the prosthesisof the '824 patent is still subject to kinking, collapsing or foldingduring and after implantation.

[0007] It is therefore desirable to provide a prosthesis including astent/graft combination which provides adequate radial support fromwithin the graft to maintain the graft in expanded condition withoutrisk of collapsing, kinking or folding.

SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to provide animplantable prosthetic device which may be implanted intraluminallywithout need for major surgical intervention.

[0009] It is a further object of the present invention to provide anintraluminally implantable stent/graft combination for use in repairinga damaged blood vessel.

[0010] It is a still further object of the present invention to providean intraluminally implantable, self-expanding stent/graft combinationwhich provides radial support for the graft so as to resist collapsing,kinking and folding during and after implantation.

[0011] In the efficient attainment of these and other objects, thepresent invention provides an implantable assembly. The assemblyincludes an elongate, generally tubular compressible graft havingopposed end portions. A pair of resiliently compressible, generallytubular stents are positioned within the graft at spaced apart locationsadjacent the end portions of the graft. A plurality of elongate strutsextend between and interconnect the stents. The struts are radiallyspaced about the inner cylindrical surface of the graft and are designedfor contact therewith, so as to provide internal radial support to thegraft when in a compressed state and to further provide radial supportalong the length of the graft after implantation.

[0012] As more particularly described by way of the preferred embodimentherein, the graft is generally a textile graft having opposed open ends.A pair of stents, each formed by wire portions arranged in a zig-zagconfiguration, are disposed at the open ends of the graft. At least fourstruts are provided to span the central portion of the graft andinterconnect the two stents. The struts are spaced such that theyprovide internal support for the graft, resisting kinking, collapsing orfolding of the graft and also are spaced and arranged in such a mannerthat thrombosis formation between the struts is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 shows, in longitudinal cross-section, the expandedintraluminal prosthesis of the present invention.

[0014]FIG. 2 shows, in longitudinal cross-section, the prosthesis ofFIG. 1 implanted in a blood vessel.

[0015]FIG. 3 shows the prosthesis of FIG. 1 in compressed condition forimplantation in a delivery catheter.

[0016]FIG. 4 is an enlarged plan view of a portion of a stent of theprosthesis of the present invention.

[0017]FIG. 5 shows, in longitudinal cross-section, a bifurcatedprosthesis of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention is directed to an implantable assembly fora diseased or damaged portion of a blood vessel or other like vessel toprovide replacement or reinforcement of the damaged vessel. Such animplantable assembly is typically referred to as a prosthesis. Referringto FIG. 1, the prosthesis of the present invention is shown generally atprosthesis 100. Prosthesis 100 includes elongate, generally tubulargraft 10. Graft 10 may be any conventional graft constructed of anymaterial known in the art. For example, graft 10 may be a textilemember, constructed of braided, knitted or woven synthetic yarns such aspolyester, or may be formed of an extruded plastic such as expandedpolytetrafluoroethylene (PTFE). Graft 10 is compressible in order topermit implantation via a delivery catheter.

[0019] Graft 10 includes first open end portion 10 a and second open endportion 10 b opposed thereto. The tubular shape of graft 10 betweenfirst open end portion 10 a and second open end portion 10 b is definedby the wall of graft 10 which includes inner surface 13. The tubularshape of graft 10 defines inner lumen 15, which is designed to permit,for instance, blood flow therethrough upon implantation.

[0020] A pair of resiliently compressible, generally tubular stents 20are positioned within graft 10 at spaced apart locations adjacent firstopen end portion 10 a and second open end portion 10 b. Stents 20 may beany type of stents known for such applications in the art, and may beconstructed of any material known in the art, such as stainless steel orother metals or alloys, polymeric materials, or composites of polymersand metal. Preferably, stents 20 are constructed of stainless steelwire. In operation, stents 24 maintain graft 10 in expanded positionagainst the wall of blood vessel 50, as depicted in FIG. 2. The presentinvention contemplates use of any type of expandable stents known in theart, for instance, self-expandable stents, balloon-expandable stents,temperature-expandable stents, and the like. In the preferredembodiments shown herein, stents 20 are of the self-expandable typebeing expandable in a radial direction between a compressed diameter anda larger expanded diameter. Stents 20 are formed in a closed zigzagconfiguration, commonly referred to as Z-stents. Such Z-stents arecommonly known in the art, and are further described in U.S. Pat. No.4,580,568 to Gianturco, incorporated herein by reference.

[0021] Stents 20 may be secured to inner surface 13 of graft 10.Preferably, this securing is accomplished by stent sutures 36, which maybe any suture known in the art. Stent sutures 36 are provided in orderto maintain stents 20 in a position adjacent first open end portion 10 aand second open end portion 10 b of graft 10. Stent sutures 36 may beattached to stent 20 at raised stent coils 37, which are capable ofaccommodating stent sutures 36 and preventing movement of the stent 20with respect to the graft 10.

[0022] As mentioned above, stents 20 are formed in a zig-zagconfiguration, as further depicted in FIGS. 1 and 4. With such aconfiguration, stents 20 are formed of wire defining a plurality of wireextents 22, with spaces 23 between adjacent wire extents 22. Wireextents 22 may exist as discrete members, with adjacent wire extents 22being connected to one another at stent joints 24 c and 24 d. In such aconfiguration, stents 20 are typically positioned at first open endportion 10 a and second open end portion 10 b of graft 10 such that aportion of stents 20 exists within inner lumen 15 of graft 10 and aportion of stents 20 exists outside of inner lumen 15 of graft 10. Inthis manner, internal stent joints 24 c are positioned within innerlumen 15 and external stent joints 24 d are positioned outside of innerlumen 15. It should be noted that in this arrangement, “internal” isbeing used to designate a general area toward the central or medial areaof implantable assembly 100, while “external” is being used to designatea general area extending distally beyond the end portions of implantableassembly 100. In such a configuration, it is preferable that stentsutures 36 securing stents 20 to graft 10 are positioned generally atintermediate portion 22 a of selected ones of wire extents 22 to provideeffective securement.

[0023] It is further contemplated that stents 20 may include anchoringbarbs 25 attached thereto. Such anchoring barbs 25 are commonly knownand used in combination with stents and are capable of engagement withblood vessel 50 to assist in anchoring prosthesis 100 in place withinblood vessel 50 after implantation. Anchoring barbs 25 are attached toselected ones of wire extents 22 and extend outside of inner lumen 15 ofgraft 10 to a position proximate to and adjacent internal stent joints24 c and external stent joints 24 d, as depicted in FIG. 4. Preferably,anchoring barbs 25 are attached generally to intermediate portion 22 aof selected ones of wire extents 22, and extend outside of graft 10. Inthis manner, anchoring barbs 25 provide an effective medially balancedanchoring means for anchoring prosthesis 100 within blood vessel 50, asdepicted in FIG. 2.

[0024] As shown in FIG. 1, prosthesis 100 further includes a pluralityof struts 40 extending between and interconnecting stents 20. Struts 40are radially spaced about inner surface 13 of graft 10, and positionedfor contact with graft 10. Preferably, struts 40 are equally radiallyspaced about inner surface 13 of graft 10. This positioning provideseffective internal support for graft 10 when in a compressed state andfurther provides radial support along the length of graft 10 when in anexpanded state after implantation. Struts 40 may be constructed of anymaterial known in the art, such as stainless steel or other metals oralloys, polymeric materials, or composites of polymers and metal,Preferably, struts 40 are constructed of similar material to stents 20,and in most preferred embodiments, both stents 20 and struts 40 areconstructed of stainless steel wire.

[0025] Struts 40 extend generally parallel with inner lumen 15 of graft10, and therefore parallel with the direction of blood flowtherethrough, as depicted in FIG. 1. Such an arrangement provideseffective support for graft 10 while reducing the likelihood ofthrombosis from occurring within graft 10.

[0026] In the preferred embodiment shown herein, prosthesis 100 includesfour struts 40 substantially equally radially spaced about inner surface13 of graft 10. With four struts 40 provided in this manner, graft 10 isprovided with sufficient radial support during and after implantation,with the likelihood of thrombosis formation being reduced.

[0027] Optionally, struts 40 may also be directly secured to graft 10using stent sutures 38. Each strut 40 may include spaced apart raisedstrut coils 39 therealong. These raised strut coils 39 which are similarto stent coils 37 described above, may accommodate strut sutures 38 in amanner shown in FIG. 1. The engagement of strut sutures 38 with strutcoils 39 helps maintain the position of graft 10 about struts 40 and tofurther provide effective securement and support for graft 10.

[0028] Struts 40 may be attached at both ends to internal stent joints24 c by any known means of attachment. Preferably, struts 40 aresoldered to internal stent joints 24 c, as depicted in FIGS. 1 and 4 atsolder joint 47. This attachment of struts 40 to internal stent joints24 c provides for effective support within prosthesis 100, and ensuresthat a proper distance will be maintained between stents 20, therebypreventing migration of the stents during and after implantation. In thepreferred embodiments, struts 40 are attached to internal stent joints24 c that do not have an anchoring barb 25 extending proximate andadjacent thereto.

[0029] While four equally spaced struts 40 are shown herein, the presentinvention contemplates use of differing numbers of plural struts. Thenumber of struts employed in each particular instance may vary with theparticular construction of stents 20. The struts 40 may be provided inone-to-one correspondence with the number of internal stent joints 24 c(FIG. 4), so that one strut 40 extends from each internal stent joint 24c. Alternatively, the struts 40 can extend from every other internalstent joint 24 c so that the number of struts 40 will be one-half thenumber of internal stent joints 24 c of each stent. While three or fourstents are contemplated as the minimum number needed to providesufficient radial support for grafts 10, a greater number of struts mayalso be employed.

[0030] In a further embodiment of the present invention as depicted inFIG. 5, a bifurcated graft 90 is provided. Bifurcated graft 90 includesfirst open end portion 90 a and second end portion 90 b, with a pair oftubular legs 91 extending from second end portion 90 b. Tubular legs 91include leg open end portions 91 a and leg attached portions 91 b, witha path of communication for blood flow from inner lumen 95 through bothtubular legs 91 and through leg open end portions 91 a. Such bifurcatedgrafts are commonly known in the art and are commonly used inimplantation procedures.

[0031] In such an embodiment, stent 20 a exists adjacent first open endportion 90 a and a second stent 20 b exists adjacent second end portion90 b, with struts 40 extending therebetween in a manner similar to thatdescribed above. However, it should be noted that in this embodiment,stent 20 b which is positioned adjacent said second end portion 90 b ispositioned entirely within inner lumen 95 of bifurcated graft 90. Suchpositioning would obviate the need for anchoring barbs thereon.

[0032] In the instant embodiment, an additional pair of resilientlycompressible, generally tubular spaced apart leg stents 29 a and 29 b ofthe type similar to stents 20, described above, may be provided withineach of tubular legs 91 adjacent leg open end portions 91 a and spacedfrom second end portion 90 b of bifurcated graft 90. Such additional legstents 29 a and 29 b maintain tubular legs 91 in contact with bloodvessel 50 in a similar manner as stents 20 a and 20 b. Leg stents 29 amay include anchoring barbs 25 to anchor leg stents 29 a to the bloodvessel in a manner similar to the preferred embodiment. Further,additional struts 49 may be included within tubular legs 91. Additionalstruts 49 are attached at both ends between leg stents 29 a and 29 b asshown in FIG. 5. Each pair of additional struts 49 extends between eachpair of leg stents 29 a and 29 b. Additional struts 49 function in asimilar manner to struts 40 in the main body portion of bifurcated graft90 in that they provide radial support to the tubular legs 91.

[0033] The prosthesis of the present invention can be implanted into thebody using any known method of implantation, for instance,transcutaneous implantation, percutaneous implantation, cut downprocedures, and the like. Preferably, the present inventive prosthesisis utilized with a deployment system capable of minimally invasivetranscutaneous insertion. Such deployment systems are known in the artand are described in U.S. Pat. No. 5,387,235 to Chuter, incorporatedherein by reference.

[0034] While the invention has been described herein in terms of certainpreferred embodiments, those skilled in the art will recognize thatvarious modifications can be made without departing from the scope ofthe present invention.

What is claimed is:
 1. An implantable assembly comprising: an elongate,generally tubular compressible graft having opposed end portions, a pairof resiliently compressible, generally tubular stents positioned withinsaid tubular graft at spaced apart locations adjacent said end portionsof said graft; and a plurality of struts extending between andinterconnecting said stents, said struts being radially spaced about theinner surface of said graft and being positioned for contact therewithto provide internal support to said graft when in a compressed state andto further provide radial support along the length of said graft afterimplantation.
 2. An implantable assembly of claim 1 further includingmeans for securing said stents in said graft adjacent said ends thereof.3. An implantable assembly of claim 2 wherein said securing meansincludes said stent being sutured to said graft.
 4. An implantableassembly of claim 1 wherein each of said stents is formed of wiredefining a plurality of wire extents arranged in a zig-zag configurationhaving spaces between adjacent wire extents.
 5. An implantable assemblyof claim 4 wherein adjacent wire extents of each of said stents areconnected at radially spaced medial stent joints and radially spaceddistal stent joints, said medial stent joints being longitudinallyspaced from said distal stent joints.
 6. An implantable assembly ofclaim 5 wherein each of said struts is an elongate member connected ateither end to said stents.
 7. An implantable assembly of claim 6 whereineach of said struts is connected at either end to one of said medialstent joints.
 8. An implantable assembly of claim 7, wherein said strutsare connected to each of said medial stent joints.
 9. An implantableassembly as in claim 7, wherein said struts are connected to alternatingones of said medial stent joints.
 10. An implantable assembly of claim 1wherein said graft is a textile graft.
 11. An implantable assembly ofclaim 1 wherein said stents are self-expanding stents.
 12. Animplantable assembly of claim 7 wherein said assembly is designed forimplantation in a blood vessel and wherein said stents are radiallyspaced apart a distance sufficient to resist thrombosis formationtherebetween.
 13. An implantable assembly of claim 7 wherein at leastone of said stents further includes anchoring barbs attached thereto,said anchoring barbs adapted for engagement with said blood vessel. 14.An implantable assembly of claim 13 wherein said anchoring barbs areattached to selected ones of said wire extents and extend to a positionproximate to and adjacent said stent joints.
 15. An implantable assemblyof claim 14 wherein said struts are attached to said stent joints otherthan said stent joints adjacent said extending anchoring barbs.
 16. Animplantable assembly of claim 15 further including means for attachingsaid struts to said stent joints.
 17. An implantable assembly of claim16 wherein said attaching means includes said struts being soldered tosaid stent joints.
 18. An implantable assembly of claim 1 wherein saidgraft is a bifurcated graft including a first open end portion, anopposed second end portion and a pair of tubular legs extending fromsaid second end portion, said tubular legs having leg open ends.
 19. Animplantable assembly of claim 18 wherein one stent of said pair ispositioned adjacent said first open end portion and the other stent ofsaid pair is positioned adjacent said second end portion.
 20. Animplantable assembly of claim 19 further including an additional firstpair of spaced apart, resiliently compressible, generally tubular stentspositioned within one of said tubular legs, and an additional secondpair of spaced apart, resiliently compressible, generally tubular stentspositioned within the other of said tubular legs, one said stent of eachof said additional first and second pairs being located adjacent eachsaid open end of each said leg.
 21. An implantable assembly of claim 19,further including an additional plurality of struts extending betweenand interconnecting said first and second additional pair of stents. 22.An implantable prosthesis comprising: an elongate, radially compressibletubular graft having an inner tubular surface, said graft having opposedfirst and second open end portions; and a stent assembly supportedwithin said tubular graft, said stent assembly comprising: a firstgenerally tubular radially self-expanding stent supported within saidgraft adjacent said first open end portion; a second generally tubularradially self-expanding stent supported within said graft adjacent saidsecond open end portion; and a plurality of struts extending between andinterconnecting said first and second stents, said struts being radiallyspaced about said inner tubular surface of said graft and in contacttherewith for providing internal support to said graft.
 23. A prosthesisof claim 22 wherein said plurality of struts includes at least fourstruts substantially equally radially spread about said inner tubularsurface of said graft.
 24. A prosthesis of claim 23 wherein said stentsand said struts are formed of metallic wire.